Hidden within the DNA of California's common ravens (Corvus corax) is the specter of another ancient raven species, The Washington Post reports. Researchers looked at the genomes of hundreds of ravens from across North America, examining mutations within the DNA to trace out their evolutionary history. They found that about 1.5 million years ago, the birds living in California split off into a separate species. After 1 million years of isolation, this lineage began breeding again with other ravens, eventually converging back into the single species of common raven that exists today. Writing in Nature Communications, the authors say that climate change is likely to cause more species to fuse together in this way.